WASHINGTON -- The United States had just two forwards available for Tuesday's game against Mexico.

The rest of the world should be so short staffed.

With Alex Morgan sidelined as a precaution as she recovers from a knee injury, the U.S. turned to Sydney Leroux to start alongside Abby Wambach. By the time the halftime whistle mercifully arrived, the fill-in had four goals, Mexico had a collective look of resignation and the only drama centered on whether Leroux would become the seventh woman to score five goals in a match for the United States.

AP Photo/Alex Brandon

Sydney Leroux did plenty of celebrating against Mexico, scoring four goals.

She settled for just the four. Much the way the U.S. settled for just a 7-0 win.

If this wasn't the A-team, or at least all of the A-team, we may need a bigger alphabet.

"There's a lot of competition in our squad," U.S. coach Tom Sermanni said. "We've got a lot of players missing from tonight's game, so I think what tonight does is, it sends a message right across the whole squad that nobody's place is safe in the team. That's important for competition, and it's important for the continued development of the team."

And as much as alliteration begs Mexico be labeled a regional rival, there was little indication it was warranted on this night.

Considering three of the past four games between neighbors had been decided by one goal, including Mexico's memorable win in World Cup qualifying that forced the United States into a playoff against Italy, it was easy to imagine that perhaps the margin for error had dwindled to such a degree that the U.S. would face the consequences of carelessness and inexperience.

It was only a friendly two years ahead of the World Cup, but perhaps it would be competitive.

Sure enough, what seemed a relatively harmless turnover at midfield in the second minute nearly proved costly for the United States. Played onside by Crystal Dunn, the fullback on the far side of the field, Mexico's Renae Cuellar found herself alone against Hope Solo and forced the keeper to come up with a solid save. A spotty clearance on the ensuing scramble in front of goal brought another sharp intake of breath from the crowd of 12,594 before the danger finally passed.

And there, the competitive drama more or less concluded.

Scoring barrage

The first goal went to Wambach in the 11th minute, her 161st international tally coming after a cross from Kristie Mewis found her all alone near the penalty spot. It was a lot of Leroux from that point forward.

Leroux's first two goals came little more than a minute apart. Both were as much about the work she did to get to where the scoring opportunities were than the finishing touch. The first, in the 21st minute, came on a short-range header after Mexican keeper Cecilia Santiago parried away a Wambach shot.

The second was another bit of opportunism when she tapped home a Santiago deflection as the ball rolled toward the goal line after a nice bit of interplay between Wambach and Lauren Holiday left the latter with a clean shot from the top of the 18-yard box.

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Morgan Brian also got into the act for the U.S., scoring her first international goal.

The 23-year-old Leroux, who entered with 17 goals in 38 appearances, looked in form because she was.

Asked if she was surprised by her night, she hesitated rather than pounce on the easy answer. Maybe she didn't expect to score four goals, she conceded, but she came in with no shortage of confidence after scoring 11 goals for the Boston Breakers in the first season of National Women's Soccer League. Not since her heyday (all right, it was only a couple of years ago) at UCLA had she played so much and so regularly.

"The NWSL was great for me," Leroux said. "Here, you don't always get 90 minutes. In Boston, I got to play a lot, and I got to learn a lot. I was playing as much soccer as possible. So to get a lot of goals in a season and to kind of figure my stuff out was very good for me."

She wasn't done with just the brace. The third goal came in the 30th minute and required the most work. Off a header from Wambach on Hope Solo's long goal kick, Leroux gathered the ball on the right side of the field at least 40 yards from goal and held off defenders as she made a diagonal beeline for the far side of the 18-yard box. The shot back toward the side of the field from which she came slipped in under Santiago.

For her final goal, she muscled her way in front of a defender in the box and headed home Holiday's well-served free kick in the 41st minute.

In 20 minutes, she scored just about every way a forward can score in the run of play.

The fans who called out for Morgan in the postgame autograph line with more gusto than any cheers during the game made the pecking order perfectly clear, but it's nice to have Leroux in the back pocket.

"I'd hate to play against Sydney Leroux as a defender," Sermanni said. "She's just non-stop. She's an amazing physical presence. She's always in there looking to score goals. She holds the ball up well. She's constantly involved in the game. She's a bit like Didier Drogba. You don't want to play against her because you know you'll be in for a tough night."

One of Leroux's closest friends, Mewis knows the feeling well as a defender asked to contend with her in both NWSL and national team training sessions.

"You definitely don't want her to get going, because if she starts running, you're done," Mewis said. "So you just have to try and slow her down and do what you can. But when she starts running with the ball, she's unstoppable, I think."

Deep roster

It wasn't just Leroux, who may be only 23 but entered the game with more caps than half the roster. Wambach's opening goal was her 20th in 20 career games against Mexico, evidence of just how long she has been a thorn in its side (not that the rest of the world gets off easy with 141 goals in 188 games). But the ball that came to her to finish was the product of two players with a total of eight appearances for the national team between them, Mewis and national team rookie Erika Tymrak combining on a give-and-go on the left side that freed Mewis for the cross.

By the end of the night, the U.S. had a lineup that included three active collegians and two other players making their first appearances for the senior national team.

Will Tymrak, who settled in well after getting the start, make a serious run at the 2015 squad? Will Mewis make the starting job hers on a full-time basis? Will Morgan Brian, who scored her first international goal in her second appearance, push her way into the crowded midfield mix?

Tuesday night didn't answer any of those questions. But the fact they are questions shows that depth remains this country's greatest soccer asset.

"It's hugely important," Sermanni said. "You're constantly looking at putting layers in place to give you many ways of development. We've now got a good youth system in place. We've got an Under-20 and Under-23 team in place. You've got the college system, you've got a semi-professional league and now we've got a full-time professional league. So the structure that's in place is becoming better and better."